The stereochemistry of the dehydrogenation of isobutyryl CoA to methacrylyl CoA will be determined. The dehydrogenated methyl will be assigned by application of chiral 13C-isobutyric acid, and 13C nmr examination of the metabolite. The dehydrogenation will be determined as cis or trans by application of isobutyric acid samples having 'chiral methyls (CHDT)'. The stereochemistry of the dehydrogenation of isovaleryl CoA to beta-methylcrotonyl CoA will be studied. The eliminated alpha-hydrogen will be assigned cis or trans by application of chiral isovaleric acid substrates. The stereochemistry of the hydration of beta-methylglutaconyl CoA will be determined. The labelled product will be converted to mevalonic acid, then to cholesterol to determine the location of the alpha-tritium atom.